1. Field of the Invention
The present invention relates to cooling of electronic devices, and particularly to heat sink assemblies with fixing devices for readily and firmly attaching a heat sink to an electronic device.
2. Related Art
Developments in today""s highly information-intensive society have led to remarkable improvements in performances of electronic devices. During operation of many contemporary electronic devices, large amounts of heat are produced. Such heat must be efficiently removed from the electronic device, to prevent the system from becoming unstable or being damaged. Typically, a heat sink is attached to an outer surface of the device to facilitate removal of heat therefrom.
A conventional heat sink assembly often uses a clip to attach a heat sink to an electronic device. The clip is placed into a channel of the heat sink and presses a top surface of a base of the heat sink. However, the channel is a space which would otherwise be occupied by a number of heat-dissipating fins. This results in lower heat dissipation efficiency of the heat sink.
Another heat sink assembly uses a clip placed under the heat sink to attach the heat sink to the electronic device. An example of such assembly is disclosed in Taiwan Patent Application No. 83204483. The clip defines a circular opening with a screw thread thereat, to engage with a complementarily threaded disc-shaped base of a heat sink. Space available for heat-dissipating fins is not compromised. However, the manufacturing process requires machining of a thread at both the opening of the clip and at the base of the heat sink. This is unduly cumbersome and time-consuming. Furthermore, it is difficult to precisely adjust the amount of pressing force exerted by the heat sink on the electronic device. If the base is rotated downwardly too much, it can easily damage the electronic device. If the base is not rotated downwardly far enough, it will not firmly contact a top face of the electronic device. This reduces the efficiency of heat dissipation. Additionally, when the assembly is subjected to vibration, the engagement between the clip and the heat sink is prone to become loose over time. The base gradually loses firm contact with the top face of the electronic device.
Therefore, an improved means of securing a heat sink to an electronic device which overcomes the above problems is desired.
Accordingly, an object of the present invention is to provide a heat sink assembly having a fixing device which firmly and reliably attaches a heat sink to a CPU.
Another object of the present invention is to provide a heat sink assembly which readily attaches a heat sink to a CPU and which allows ready detachment of the heat sink from the CPU.
To achieve the above-mentioned objects, a heat sink assembly comprises a heat sink, a fixing device, and a fan. The heat sink has a base, an engaging body, and an annular groove defined in a periphery of a topmost portion of the engaging body. A plurality of external teeth extends outwardly from a periphery of the engaging body. A plurality of radial fins extends upwardly from the base. A protrusion extends outwardly from a bottom portion of one fin, and an engaging space is defined adjacent the protrusion. The fins cooperatively define a central space for accommodating the fan therein. The fixing device has a frame defining an engaging opening. A plurality of internal teeth extends inwardly from the frame at the opening. The internal teeth are engaged in the groove against the external teeth of the heat sink. The fixing device also has a stop tab accommodated in the engaging space, and a latch extending coplanarly and horizontally from the stop tab. The stop tab abuts the protrusion, and the latch presses against the protrusion.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention together with the attached drawings, in which: